Light Measuring Device

CROSS-REFERENCE TO RELATED APPLICATION

The application claims priority under 35 U.S.C. § 119(a) to Korean Patent Application No. 10-2023-0069506, filed on May 30, 2023, the disclosure of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present invention relates to a light measuring device. DISCUSSION OF THE RELATED ART As information technology continues to further develop, the importance of a display device as a connection medium between a user and information continues to increase. In response to this, the use of display devices such as a liquid crystal display device and an organic light emitting display device is increasing. Recently, a near eye display device for realizing AR (Augmented Reality) or VR (Virtual Reality) is under development. A light measuring device may be desirable to check whether the near eye display device accurately displays an image to a human eye. However, in a case of the near eye display device, since a distance between a display device and the eye may be very small and a structure of the human eye (e.g., size and location of the iris, pupil, retina, etc.) should be considered, it might not be accurate to evaluate light characteristics using a conventional light measuring device.

SUMMARY

According to an embodiment of the present invention, a light measuring device includes: a first lens; a first variable opening located in a first direction from the first lens at a predetermined distance; a second lens located in the first direction from the first variable opening at a predetermined distance; a second variable opening located in the first direction from the second lens; a third lens located in the first direction from the second variable opening; and a light receiving unit located in the first direction from the third lens at a predetermined distance, wherein a diameter of the first variable opening and a diameter of the second variable opening are independently adjusted. In an embodiment of the present invention, the first lens includes a convex surface protruding in the first direction. In an embodiment of the present invention, the second lens includes a convex surface protruding in a direction opposite to the first direction. In an embodiment of the present invention, the third lens includes a convex surface protruding in the first direction. In an embodiment of the present invention, the second variable opening includes a plurality of partial openings arranged in a second direction that is different from the first direction. In an embodiment of the present invention, n partial openings among the plurality of partial openings are in an open state when the second variable opening has a first diameter, and m partial openings among the plurality of partial openings are in an open state when the second variable opening has a second diameter, wherein n and m are integers greater than 0, and wherein m is greater than n when the second diameter is greater than the first diameter. In an embodiment of the present invention, each of the plurality of partial openings includes: a transparent layer; a plurality of electronic ink capsules positioned inside the transparent layer; and a first electrode. In an embodiment of the present invention, in each of the plurality of partial openings, the first electrode is located on an upper surface of the transparent layer. In an embodiment of the present invention, each of the plurality of partial openings further includes: a second electrode that is insulated from the first electrode. In an embodiment of the present invention, the second electrode is located on a side surface of the transparent layer. In an embodiment of the present invention, the second electrode is located on a lower surface of the transparent layer. In an embodiment of the present invention, each of the plurality of partial openings further includes: a third electrode located on a side surface of the transparent layer. In an embodiment of the present invention, each of the plurality of partial openings is in an open state when a voltage is applied to the first electrode. In an embodiment of the present invention, each of the plurality of partial openings is in a blocked state when the voltage is not applied to the first electrode. In an embodiment of the present invention, each of the plurality of partial openings is in an open state when a voltage is applied to the first electrode. In an embodiment of the present invention, each of the plurality of partial openings is in a blocked state when a voltage is applied to the second electrode. In an embodiment of the present invention, a distance between the first lens and the second lens is larger than a distance between the second lens and the third lens. In an embodiment of the present invention, the first lens further includes a flat surface facing in a direction opposite to the first direction. In an embodiment of the present invention, the second lens further includes a flat surface facing in the first direction. In an embodiment of the present invention, the third lens further includes a flat surface facing in a direction opposite to the first direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will become more apparent by describing in further detail exemplary embodiments thereof with reference to the accompanying drawings, in which: FIG. 1 is a diagram illustrating a light measuring device according to an embodiment of the present invention. FIGS. 2 and 3 are diagrams illustrating a second variable opening according to an embodiment of the present invention. FIG. 4 is a diagram illustrating an electronic ink capsule. FIGS. 5 and 6 are diagrams illustrating a process of adjusting a diameter of the second variable opening. FIGS. 7 , 8 and 9 are diagrams illustrating a second variable opening according to an embodiment of the present invention.

DETAILED

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may be embodied in various different forms and is not limited to the embodiments described herein. The same or similar components are denoted by the same reference numerals throughout the specification and the drawings, and a repeated description of the same components may be omitted or briefly discussed. Therefore, the reference numerals described above may also be used in other drawings. In the drawings, various thicknesses, lengths, and angles are shown and while the arrangement shown does indeed represent an embodiment of the present invention, it is to be understood that modifications of the various thicknesses, lengths, and angles may be possible within the spirit and scope of the present invention and the present invention is not necessarily limited to the particular thicknesses, lengths, and angles shown. In addition, in the description, the expression “the same” may mean “substantially the same”. That is, it may be the same enough to convince those of ordinary skill in the art to be the same. In other expressions, “substantially” may be omitted. FIG. 1 is a diagram illustrating a light measuring device according to an embodiment of the present invention. Referring to FIG. 1 , a display device DD and a light measuring device ESTD are shown as an example. The display device DD may include a conventional display panel for displaying an image, such as a liquid crystal display panel or an organic light emitting display panel. It is assumed that the display panel has a plane extending in second and third directions DR 2 and DR 3 . For example, the display panel may have a completely flat surface or a curved surface. The display device DD may be a near eye display device for realizing Augmented Reality (AR) or Virtual Reality (VR). The display device DD may display an image in a first direction DR 1 . The first direction DR 1 , the second direction DR 2 , and the third direction DR 3 may be substantially perpendicular to each other. Light PRY 1 constituting the image may be emitted from the center of the display device DD. Another light MRY constituting the image may be emitted from the edge of the display device DD. Another light PRY 2 constituting the image may be emitted at an arbitrary position between a position where the light PRY 1 is emitted and a position where the light MRY is emitted in the display device DD. The light measuring device ESTD may include a first lens LNS 1 , a first variable opening VOPN 1 , a second lens LNS 2 , a second variable opening VOPN 2 , a third lens LNS 3 , and a light receiving unit SS. The light measuring device ESTD may be positioned in the first direction DR 1 at a predetermined distance from the display device DD. Centers of the display device DD, the first lens LNS 1 , the first variable opening VOPN 1 , the second lens LNS 2 , the second variable opening VOPN 2 , the third lens LNS 3 , and the light receiving unit SS may be aligned with each other in the first direction DR 1 . The first lens LNS 1 may include a convex surface protruding in the first direction DR 1 . For example, the convex surface of the first lens LNS 1 may face the first variable opening VOPN 1 . The first lens LNS 1 may further include a flat surface in a direction opposite to the first direction DR 1 . In an embodiment of the present invention, the first lens LNS 1 may further include a convex surface in a direction opposite to the first direction DR 1 . The first variable opening VOPN 1 may be located in the first direction DR 1 from the first lens NS 1 . For example, the light measuring device ESTD may further include a mechanical driving device such as a motor or an actuator. The first variable opening VOPN 1 may be a mechanical aperture whose diameter is controlled by the motor and/or a controller. A diameter of the first variable opening VOPN 1 may be defined on a plane in the second and third directions DR 2 and DR 3 . For example, the size of the diameter of the first variable opening VOPN 1 may be adjusted according to the size of a measurement area (for example, the size of an image displayed by the display device DD), a distance between the display device DD and the light measuring device ESTD, and the like. The second lens LNS 2 may be located in the first direction DR 1 from the first variable opening VOPN 1 . The second lens LNS 2 may include a convex surface facing in a direction opposite to the first direction DR 1 . For example, the convex surface of the second lens LNS 2 may protrude in the direction opposite to the first direction DR 1 . The second lens LNS 2 may further include a flat surface facing in the first direction DR 1 . In an embodiment of the present invention, the second lens LNS 2 may further include a convex surface in the first direction DR 1 . The second variable opening VOPN 2 may be located in the first direction DR 1 from the second lens LNS 2 . For example, a diameter of the second variable opening VOPN 2 may be adjusted independently of the diameter of the first variable opening VOPN 1 . The diameter of the second variable opening VOPN 2 may be defined on a plane in the second and third directions DR 2 and DR 3 . For example, the second variable opening VOPN 2 may function like a pupil of a human eye. For example, the diameter of the second variable opening VOPN 2 may be adjusted within a range of about 0.5 mm to about 8 mm. In a relatively dark environment, the diameter of the second variable opening VOPN 2 may be increased to increase the amount of light received. In addition, in a relatively bright environment, the diameter of the second variable opening VOPN 2 may be reduced, and a diffraction effect caused by outside light may be reduced, thereby obtaining a clear image with reduced noise. The third lens LNS 3 may be located in the first direction DR 1 from the second variable opening VOPN 2 . For example, the second variable opening VOPN 2 may be positioned between the second lens LNS 2 and the third lens LNS 3 . The third lens LNS 3 may include a convex surface facing in the first direction DR 1 . For example, the convex surface of the third lens LNS 3 may protrude in the first direction DR 1 . The third lens LNS 3 may further include a flat surface facing in a direction opposite to the first direction DR 1 . In an embodiment of the present invention, the third lens LNS 3 may further include a convex surface facing in a direction opposite to the first direction DR 1 . According to an embodiment of the present invention, the second lens LNS 2 , the second variable opening VOPN 2 , and the third lens LNS 3 may be configured as an integrated variable opening lenses. A distance between the first lens LNS 1 and the second lens LNS 2 may be larger than a distance between the second lens LNS 2 and the third lens LNS 3 . The light receiving unit SS may be located in the first direction DR 1 from the third lens LNS 3 by a predetermined distance. The light receiving unit SS may be an image sensor. For example, the light receiving unit SS may be a complementary metal oxide semiconductor (CMOS) sensor. FIGS. 2 and 3 are diagrams illustrating a second variable opening according to an embodiment of the present invention. FIG. 4 is a diagram illustrating an electronic ink capsule. Referring to FIG. 2 , a second variable opening VOPN 2 a according to an embodiment of the present invention may include a plurality of partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 . The plurality of partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 may be arranged in the second direction DR 2 . Although only four partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 are shown here, the number of partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 included in the second variable opening VOPN 2 a may be more or less than four. In addition, in other drawings including FIG. 2 , only a side of the second variable opening VOPN 2 a is shown to show a light path in the first direction DR 1 . However, referring to FIG. 3 , the plurality of partial openings PAP 1 , PAP 2 , PAP 3 , PAP 4 , . . . included in the second variable opening VOPN 2 a may be arranged on a plane in the second and third directions DR 2 and DR 3 . For example, the plurality of partial openings PAP 1 , PAP 2 , PAP 3 , PAP 4 , . . . may be arranged in a matrix form on a plane in the second and third directions DR 2 and DR 3 . Each of the partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 may include a transparent layer LQL 1 , LQL 2 , LQL 3 , or LQL 4 , a plurality of electronic ink capsules CPS 1 , CPS 2 , CPS 3 , or CPS 4 , and a first electrode EL 11 , EL 12 , EL 13 , or EL 14 . The transparent layer LQL 1 , LQL 2 , LQL 3 , or LQL 4 may be formed of a transparent gas, liquid, or solid. For example, the transparent layer LQL 1 , LQL 2 , LQL 3 , and LQL 4 may be a liquid polymer layer. The plurality of electronic ink capsules CPS 1 , CPS 2 , CPS 3 , and CPS 4 may be positioned inside the transparent layers LQL 1 , LQL 2 , LQL 3 , and LQL 4 , respectively. In addition, even though four electronic ink capsules CPS 1 , CPS 2 , CPS 3 , or CPS 4 are illustrated in each of the transparent layers LQL 1 , LQL 2 , LQL 3 , or LQL 4 , the present invention is not limited thereto. For example, the number of electronic ink capsules CPS 1 , CPS 2 , CPS 3 , or CPS 4 may be less than or greater than four. In addition, even though four transparent layers LQL 1 , LQL 2 , LQL 3 , and LQL 4 are illustrated, the present invention is not limited thereto. For example, the number of transparent layers LQL 1 , LQL 2 , LQL 3 , and LQL 4 may be less than or greater than four. The first electrodes EL 11 , EL 12 , EL 13 , and EL 14 may be disposed on the transparent layers LQL 1 , LQL 2 , LQL 3 , and LQL 4 , respectively. For example, the first electrode EL 11 , EL 12 , EL 13 , or EL 14 may be arranged in the second direction DR 2 with the transparent layer LQL 1 , LQL 2 , LQL 3 , or LQL 4 . For example, the first electrode EL 11 , EL 12 , EL 13 , or EL 14 may be disposed on an upper surface of the transparent layer LQL 1 , LQL 2 , LQL 3 , or LQL 4 . In an embodiment of the present invention, the first electrode EL 11 , EL 12 , EL 13 , or EL 14 may be arranged in a direction, which is opposite to the second direction DR 2 , with the transparent layer LQL 1 , LQL 2 , LQL 3 , or LQL 4 . The first electrode EL 11 , EL 12 , EL 13 , or EL 14 may include a transparent conductive material. For example, the first electrode EL 11 , EL 12 , EL 13 , or EL 14 may include at least one of silver nanowires (AgNW), indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), antimony zinc oxide (AZO), indium tin zinc oxide (ITZO), zinc oxide (ZnO), tin oxide (SnO 2 ), carbon nanotubes, and/or graphene. Referring to FIG. 4 , an example of the electronic ink capsule CPS 1 is shown. The electronic ink capsule CPS 1 may include a transparent liquid TPL, first ink particles BIP, and second ink particles WIP. The transparent liquid TPL may provide fluidity of positions of the first ink particles BIP and the second ink particles WIP. For example, the first ink particles BIP and the second ink particles WIP may flow throughout the transparent liquid TPL. The first ink particles BIP may be negatively charged particles. The first ink particles BIP may be black particles. In another example, the first ink particles BIP may be positively charged particles. The second ink particles WIP may be positively charged particles. The second ink particles WIP may be white particles. In another example, the second ink particles WIP may be negatively charged particles. In an embodiment of the present invention, the electronic ink capsule CPS 1 might not include the second ink particles WIP, but may include only the transparent liquid TPL and the first ink particles BIP. When no voltage is applied to the first electrode EL 11 , EL 12 , EL 13 , or EL 14 , the first ink particles BIP and the second ink particles WIP may be randomly distributed throughout the corresponding electronic ink capsule CPS 1 , CPS 2 , CPS 3 , or CPS 4 . Accordingly, as shown in FIG. 2 , the second variable opening VOPN 2 a may block all light RAY. In this case, a diameter of the second variable opening VOPN 2 a may be 0. FIGS. 5 and 6 are diagrams for explaining a process of adjusting a diameter of the second variable opening. As described above, when no voltage is applied to the first electrode EL 11 , EL 12 , EL 13 , or EL 14 , each of the plurality of partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 may be in a blocked state. For example, in a blocked state, light RAY might not travel through at least some of the transparent liquid TPL and the transparent layer LQL 1 , LQL 2 , LQL 3 , and LQL 4 of the electronic ink capsules CPS 1 , CPS 2 , CPS 3 , and CPS 4 . In addition, when a voltage is applied to the first electrode EL 11 , EL 12 , EL 13 , or EL 14 , each of the plurality of partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 may be in an open state. For example, when a positive voltage is applied to the first electrode EL 11 , EL 12 , EL 13 , or EL 14 , the first ink particles BIP may be aligned in a direction close to or a direction toward the first electrode EL 11 , EL 12 , EL 13 , or EL 14 , and the second ink particles WIP may be aligned in a direction away from the first electrode EL 11 , EL 12 , EL 13 , or EL 14 . Accordingly, the light RAY may pass through the transparent liquid TPL and the transparent layer LQL 1 , LQL 2 , LQL 3 , or LQL 4 of the electronic ink capsules CPS 1 , CPS 2 , CPS 3 , and CPS 4 . In addition, when a negative voltage is applied to the first electrode EL 11 , EL 12 , EL 13 , or EL 14 , the second ink particles WIP may be aligned in a direction close to or a direction toward the first electrode EL 11 , EL 12 , EL 13 , or EL 14 , and the first ink particles BIP may be aligned in a direction away from the first electrode EL 11 , EL 12 , EL 13 , or EL 14 . Accordingly, the light RAY may pass through the transparent liquid TPL and the transparent layer LQL 1 , LQL 2 , LQL 3 , or LQL 4 of the electronic ink capsules CPS 1 , CPS 2 , CPS 3 , and CPS 4 . Referring to FIG. 5 , a case where the second variable opening VOPN 2 a has a first diameter is shown. In this case, among the plurality of partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 , n partial openings PAP 2 and PAP 3 may be in an open state, where n may be an integer greater than 0. In the case of FIG. 5 , n may be 2. Referring to FIG. 6 , a case where the second variable opening VOPN 2 a has a second diameter is shown. In this case, among the plurality of partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 , m partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 may be in an open state, where m may be an integer greater than 0. In the case of FIG. 6 , m may be 4. When the second diameter is greater than the first diameter, m may be greater than n. FIGS. 7 to 9 are diagrams illustrating a second variable opening according to an embodiment of the present invention. Referring to FIG. 7 , each of the plurality of partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 of the second variable opening VOPN 2 b may further include a second electrode EL 21 , EL 22 , EL 23 , or EL 24 that is insulated from the first electrode EL 11 , EL 12 , EL 13 , or EL 14 . The second electrode EL 21 , EL 22 , EL 23 , or EL 24 may be located in a direction opposite to the second direction DR 2 from the transparent layer LQL 1 , LQL 2 , LQL 3 , or LQL 4 . For example, the second electrode EL 21 , EL 22 , EL 23 , and EL 24 may be positioned on a side of the transparent layer LQL 1 , LQL 2 , LQL 3 , and LQL 4 that is opposite to the side on which the first electrode EL 11 , EL 12 , EL 13 , and EL 14 is disposed. For example, the second electrode EL 21 , EL 22 , EL 23 , and EL 24 may be disposed on a lower surface of the transparent layer LQL 1 , LQL 2 , LQL 3 , and LQL 4 . The second electrode EL 21 , EL 22 , EL 23 , or EL 24 may include a transparent conductive material. For example, the second electrode EL 21 , EL 22 , EL 23 , or EL 24 may include at least one of silver nanowires (AgNW), indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), antimony zinc oxide (AZO), indium tin zinc oxide (ITZO), zinc oxide (ZnO), tin oxide (SnO 2 ), carbon nanotubes, and graphene. According to the present embodiment, to set each of the plurality of partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 to an open state, voltages that have different polarities from each other may be applied to the first electrode EL 11 , EL 12 , EL 13 , or EL 14 and the second electrode EL 21 , EL 22 , EL 23 , or EL 24 . For example, when a positive voltage is applied to the first electrode EL 11 , EL 12 , EL 13 , or EL 14 and a negative voltage is applied to the second electrode EL 21 , EL 22 , EL 23 , or EL 24 , the first ink particles BIP may be aligned by moving in the second direction DR 2 , and the second ink particles WIP may be aligned by moving in a direction opposite to the second direction DR 2 . Referring to FIG. 8 , each of the plurality of partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 of the second variable opening VOPN 2 c may further include a third electrode EL 31 , EL 32 , EL 33 , or EL 34 . The third electrode EL 31 , EL 32 , EL 33 , or EL 34 may be located in a direction opposite to the first direction DR 1 from the transparent layer LQL 1 , LQL 2 , LQL 3 , or LQL 4 . For example, the third electrode EL 31 , EL 32 , EL 33 , or EL 34 may be disposed on a side surface of the transparent layer LQL 1 , LQL 2 , LQL 3 , and LQL 4 that extends in second direction DR 2 and may be disposed adjacent to the first electrode EL 11 , EL 12 , EL 13 , and EL 14 . In an embodiment of the present invention, the third electrode EL 31 , EL 32 , EL 33 , or EL 34 may be located in the first direction DR 1 from the transparent layer LQL 1 , LQL 2 , LQL 3 , or LQL 4 . The third electrode EL 31 , EL 32 , EL 33 , or EL 34 may include a transparent conductive material. For example, the third electrode EL 31 , EL 32 , EL 33 , or EL 34 may include at least one of silver nanowires (AgNW), indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), antimony zinc oxide (AZO), indium tin zinc oxide (ITZO), zinc oxide (ZnO), tin oxide (SnO 2 ), carbon nanotubes, and/or graphene. According to the present embodiment, to set each of the plurality of partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 to a blocked state, a voltage may be applied to the third electrode EL 31 , EL 32 , EL 33 , and EL 34 . For example, when a positive voltage is applied to the third electrode EL 31 , EL 32 , EL 33 , or EL 34 , the first ink particles BIP may be aligned by moving in a direction opposite to the first direction DR 1 , and the second ink particles WIP may be aligned by moving in the first direction DR 1 . In addition, when a negative voltage is applied to the third electrode EL 31 , EL 32 , EL 33 , or EL 34 , the first ink particles BIP may be aligned by moving in the first direction DR 1 , and the second ink particles WIP may be aligned by moving in a direction opposite to the first direction DR 1 . The light shielding effect may be increased in the case of FIG. 8 than in the case where the plurality of partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 do not include the third electrode EL 31 , EL 32 , EL 33 , or EL 34 . The second variable opening VOPN 2 d of FIG. 9 illustrates an embodiment of the present invention in which each of the plurality of partial openings PAP 1 , PAP 2 , PAP 3 , and PAP 4 includes both the second electrode EL 21 , EL 22 , EL 23 , or EL 24 and the third electrode EL 31 , EL 32 , EL 33 , or EL 34 . The second variable opening VOPN 2 d may perform all of the functions described in FIGS. 7 and 8 . Duplicate descriptions thereof may be omitted or briefly discussed. The present invention may provide a light measuring device suitable for evaluating light characteristics of a near eye display device. While the present invention has been particularly shown and described with reference to embodiments thereof, it will be apparent those of ordinary skill in the art that various changes in form and detail may be made thereto without departing from spirit and scope of the present invention.